Functional coatings with exceptional surface properties, such as liquid-repellency and low-friction/adhesion, have been commonly prepared by combining textured surfaces with long-chain perfluorinated compounds. However, unfortunately, the chemical and physical effects of the LPFCs on human health and environment have been viewed lately with concern. In addition, once such artificial surfaces are physically and chemically damaged, they permanently lose their surface properties. In contrast, some living things maintain their surface properties through secretion of plant waxes and mucus. Here, we report on novel coatings inspired by such biological systems . To realize long-lasting surface properties, we have particularly focused on the syneresis of organogels, which were prepared by hydrosilylation of 2 types of silicones, and several guest organic liquids (Fig.A). As compatibility between guest liquids and polymer matrixes (cross-linked polydimethylsiloxane) is decreased to a certain critical point which is induced by the chemical and/or physical effects, the guest liquids begins to gradually leach out to the outmost organogel surface. Thanks to this self-lubricating property, adhesion of various objects was effectively reduced, resulting in the excellent anti-sticking properties. Viscous liquids flowed on the syneretic organogel surface more freely than that of non-syneretic organogel surface (Fig. B and C). For the purpose of anti-icing applications, we tuned the critical incompatibility point our organogels, which possess reversible thermo-responsive secretion nature (Fig. D). In this case, the syneresis gradually starts when the temperature is cooled (&lt; 0°C) and the syneresis liquids returns back into the organogel again by heating to room temperature. Thanks to this smart surface property, an ice-pillar formed on the organogel at -15°C easily slid off without any additional force. Furthermore, we have successfully demonstrated regeneration of superhydrophobicity artificially mimicking lotus leaves using n-octadecyltrichlorosilane as an active guest liquid (Fig. E and F). Our technique, demonstrated here, undoubtedly shows great potential for application in dynamic, multifunctional, and self-recovering coatings.

Anti-stick coatings using self-lubricating organogels (SLUGs)

251st National Meeting (2016)

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